Problem: Ming throws a stone off a bridge into a river below. The stone's height (in meters above the water), $x$ seconds after Ming threw it, is modeled by: $h(x)=-5(x-1)^2+45$ How many seconds after being thrown will the stone reach its maximum height?
Explanation: The stone's height is modeled by a quadratic function, whose graph is a parabola. The maximum height is reached at the vertex. So in order to find when that happens, we need to find the vertex's $x$ -coordinate. The function $h(x)$ is given in vertex form. The vertex of $-5(x-{1})^2{+45}$ is at $({1},{45})$. In conclusion, the stone will reach its maximum height $1$ second after being thrown.